Update grav_tips.md

Author: hpjeonGIT

grav_tips.md

@@ -20,7 +20,8 @@
     - Edit user/config/system.yaml for extra: true
     - Not recommended to have extra markdown
 - In learn2 theme, code block or fenced paragraph shows an indent at the first line
-  - Default theme is OK
+  - Quark theme is OK
+  - No cause found. Installing hightlight plugin solves the problem including blank line issues
 
 - Using anchor
   - In a page to be referred, add anchor as :  `<a name="paraview">ParaView</a>`